Q fever is an infectious disease, caused by the bacterium Coxiella burnetii, which affects both animals and humans. It has been reported to be present in a wide range of species, including cattle, sheep and goats, as well as birds and arthropods in many areas of the world. It was first recognised as a disease that could be transmitted between animals and humans, that is a zoonotic disease, in abattoir workers affected by this illness in 1935 in Australia.
Infection with Coxiella burnetii rarely leads to the development of Q fever in animals. When it does occur, the disease may cause reproductive complications including miscarriages in particular in goats. In humans, Q fever may induce flu-like symptoms, including fever and headache, diarrhoea and vomiting. In some severe cases it can cause pneumonia and hepatitis. Chronic Q fever (characterised by an infection lasting more than 6 months) is an uncommon but much more serious disease.
Human infections mainly result from the inhalation of dust contaminated with bacteria from the placenta and birth fluids or faeces from infected animals. Other modes of transmission, such as through contaminated water or the faeces of infected arthropods are rare.